An electromagnetic relay of this type is known in which a long insulating distance of small height is capable of being obtained, as set forth in the specification of British Patent No. 2167902.
More specifically, as shown in FIGS. 24 and 25, an electromagnet block 3 is housed within a box-shaped case 1, and an L-shaped movable iron element 5 is turnably supported via a hinge spring 4 fixed to a yoke 3a included in the electromagnet block 3. The interior of the case 1 is divided by a partitioning wall 1a into a compartment in which the electromagnet block 3 is accommodated and a compartment in which a contact mechanism is accommodated. The contact mechanism is composed of a movable contactor 7 having a movable contact 7a, and a fixed contactor 8 having a fixed contact 8a. The movable iron element 5 and the movable contactor 7 are connected by a card 6 that is capable of sliding movement. In order to insulate the electromagnet block 3 from the movable contactor 7 and fixed contactor 8, an insulating member 9 is attached to the compartment of the electromagnet block 3. A base 2 is fitted on the case 1.
When the movable iron element 5 is turned by excitation of the electromagnet block 3, one end of the movable iron element 5 pushes one end face of the card 6, and the card 6 thus pushed presses the free end of the movable contactor 7, whereby the latter is flexed. As a result, the movable contact 7a contacts the fixed contact 8a.
In the electromagnetic relay of this type, however, the card 6 is situated in close proximity to the base 2. Consequently, a problem encountered is that if the base 2 is deformed by an external force or as the result of thermal expansion, the sliding movement of the card 6 will be impeded and faulty operation will occur.
In the electromagnetic relay constructed as set forth above, the card 6 has a slender, elongated shape in order to assure a long insulating distance between the contacts 7, 8 and the movable iron element 5. As a consequence, the card 6 is easily deformed and the operating characteristic of the electromagnetic relay changes easily owing to curvature of the card 6 or thermal expansion.
Moreover, wear fragments are produced from one end portion of the card owing to sliding contact between the card 6 and movable contactor 7, and there is the danger that the wear fragments give rise to faulty contact.
A further problem is that in a case where a large current flows into the movable contactor 7, the card is readily melted by heat produced by the movable contactor 7. This is hazardous.
In an electromagnetic relay of the foregoing construction, the insulating member 9, which is separate from the case 1, must be installed in the compartment of the electromagnet block 3 in order to assure the long insulating distance, as set forth above. As a result, there are a large number of component parts and a large number of assembly steps. Moreover, since an adjustment operation must be performed after the internal components such as the electromagnet block 3 are installed in the box-shaped case 1, locations at which the adjustments can be made are limited and productivity is low because labor is involved in performing the adjustment operation.